Quick and weird problem for any of you clever folk! 
Just played HL2 Ep2 yesterday (finally!
) and now I'm feeling all nostalgic and want to play through HL1/Op Force/Blue Shift.
Just fired it up and got through all the nonsense in the test chamber and have discovered a major flaw. Firstly auto aim was on - eugh! However after turning it off my aim is off.
When I fire all my bullets I hit roughly an inch to the right and a little bit above the target indicated by the crosshairs.
Whilst I could just make some new crosshairs to counter this is there a known fix? Playing on the following system:
Q6600
9800GT (dunno drivers)
4GB RAM
Vista 64
Playing HL through Steam running at 1920*1200/32 bit colour
Any good ideas? Or bad ideas for that matter?

Just played HL2 Ep2 yesterday (finally!

Just fired it up and got through all the nonsense in the test chamber and have discovered a major flaw. Firstly auto aim was on - eugh! However after turning it off my aim is off.
When I fire all my bullets I hit roughly an inch to the right and a little bit above the target indicated by the crosshairs.
Whilst I could just make some new crosshairs to counter this is there a known fix? Playing on the following system:
Q6600
9800GT (dunno drivers)
4GB RAM
Vista 64
Playing HL through Steam running at 1920*1200/32 bit colour
Any good ideas? Or bad ideas for that matter?